Operation not allowed after ResultSet closed

stmt = conn.createStatement() ;
   rs = stmt.executeQuery("SELECT id, name FROM user") ;
   //process results
   while(rs.next()){
    int id = rs.getInt("id") ;
    String name = rs.getString("name") ;
    System.out.print("id: " + id) ;
    System.out.print("name: " + name) ;
    System.out.print("\n------------\n") ;    
   }
     stmt.executeUpdate("INSERT INTO user(name,password,age,sex,birthday)" +
          "VALUES('sun','www.mldn.cn',30,'男','2008-08-27')",Statement.RETURN_GENERATED_KEYS) ;
   ResultSet newid = stmt.getGeneratedKeys() ;
   newid.next() ;
   int id1 = newid.getInt(1) ;
   System.out.println(id1) ; 

    ResultSetMetaData meta = rs.getMetaData() ;
   n = meta.getColumnCount() ;
   System.out.println("number of columns --> " + n) ;
   for(i=1;i<=n;i++){
    System.out.println(meta.getColumnName(i) + "***" + meta.getColumnTypeName(i)) ;
   }

一個stmt生成多個ResultSet對象，在rs全部操做完成以後（連續）才能進行另外一個ResultSet對象newid的操做，不然像上述狀況就會出現Operation not allowed after ResultSet closed異常